It would seem that most of you have missed the point, the most important thing is to get a fix out just before you hit the water that way you take the "search" out of search and reascue !.
Thirty feet above the water D & D won't hear you, London info won't hear you and any radar unit you might be working won't hear you but a large number of airliners WILL hear you because they are all listening to 121.5 these days.
Speed of rescue is vital as your life expectancy in the sea is very short and if the rescue guys know the correct place to look you will increase your chances ten fold. now go back and read my first post on this subject and think about using ALL the assets that are avalable to you and how to use them to your best advantage.